This invention relates to a security bar to prevent or restrict the opening of a door.
Entrance to a dwelling is normally controlled by a hinged door that is equipped with locks such as mortice locks, dead bolts and the like, in order to prevent entrance. Sliding bolts at the side, top or bottom of the door can be installed to provide further security against unauthorized entry.
While the installation of locks can adequately prevent the door from being opened, it is desirable on many occasions to open the door a few inches to create a clear gap between the door and the door frame, in order to be able to address the person outside, i.e. to speak to them "face to face". It may be necessary to pass a document that needs a signature, to inspect credentials or simply to receive an envelope or paper. It is also not considered good manners to talk through a closed door. There is therefore a need for a device that allows the door to be opened a distance that provides a clear gap between the door and the door frame, after the locks are disengaged. There of course is also a need for a device which supplements the ordinary door locks when the door is closed and locked.
The most commonly used device that allows the door to be opened a small distance and still provide a degree of protection against unauthorized entry, is the well-known door chain. This chain is fastened to both the door and the door frame on the inside of the door. The chain can be unfastened by sliding it to the end of the slotted fitting. The chain is positioned in such a way that it can only be unfastened when the door is closed. With the chain in place the door can be opened a few inches but it remains secured.
The problem with these chains is that unless the chain is an unusual heavy gauge and even more important, unless the chain is fastened with very strong (long screws, it can be dislodged or broken fairly easily by applying force to the door. The chains that are commonly sold in hardware stores in North America are not very strong and the screws that secure the ends of the chain or its fittings to the door and to the door jamb are typically 3/4 inch long and not very strong. When the door is partly opened, it is also fairly easy to cut the chain from the outside with bolt cutters or break it by hitting it with a steel bar. Chains are therefore only effective if the person on the outside is willing to respect the imposed restriction of entry.
Another common device that is now often used provides more protection than a door chain. These are security brackets that consist of an elongated loop made of 1/8.times.inch steel that is fastened with a hinge to the door frame. A curved pin with a thicker, spherical end is fastened with screws to the inside of the door. When the door is in the closed position, the hinged loop can engage the curved pin. When the door is opened, the round end of the pin moves to the end of the loop and the length of the loop is the distance that the door can be opened. Although this bracket provides more protection than a door chain, it is exposed to the intruder when the door is opened and the bracket can be jimmied quite easily because it is only fastened to the door frame with two screws.
If the person on the outside has criminal intentions and wants to disregard the restriction to entry, a phenomenon that is now known as "home invasion", the door chain or security bracket provides little or no real protection. There have been a number of incidents where the door was forced open with criminal intent, resulting in robberies and often injuries to the occupants.
One device that provides additional security and keeps a door closed even in the event that the locks are disengaged, is a bar that is positioned at an angle of about 60 degrees to the horizontal plane, between the door and the floor. When an attempt is made to forcibly open the door, this bar or brace will transfer a portion of the force exerted on the door to the floor and prevent opening of the door. These security bars are effective because they cannot be removed or broken by jimmying the door and they are effective when the locks are picked or opened with pass keys.
In a typical version, these bars have a foot that is equipped with a skid-resistant rubber pad which is effective because the typical 60 degree angle of the bar directs a portion of the force that is exerted on the door in a vertical direction downwards, and provides a strong force that presses the foot against the floor thereby preventing skidding of the foot that would result in making the bar ineffective. Many bars are equipped, at the top end that touches the door, with a Y-shaped section that fits under the doorknob.
While these various versions of security bars are effective in keeping the door in the closed position, one common deficiency of most of these devices is that the bar needs to be removed completely before the door can be opened. The door cannot be opened, even a small distance, in order to address the caller face to face. The protection that is provided by the security bar is then lost and the occupant again depends on a door chain, if they are installed, to prevent the door from being opened farther.